Conventional tires include a tread with a tread pattern that, when the tire is loaded, defines a footprint providing a frictional engagement with the road. The tread pattern is segmented into a plurality of raised blocks defined and separated by intersecting circumferential and transverse grooves. The grooves are necessary to provide flexibility and water removal while the blocks determine the control, acceleration and braking characteristics of the tire. The circumferential grooves are positioned such that the raised blocks are arranged in columns that extend circumferentially about the tire circumference.
The block dimensions, the number of ribs, and the inclination angle of the transverse grooves cooperate in determining the overall performance of the pneumatic tire. In particular, these factors determine the amount of tread that contacts the road, and hence the traction and control of the vehicle riding on the tires. The nonskid or groove depth determines the ability of the intersecting circumferential and transverse grooves to channel water.
In a new condition, tread patterns are designed with compromises between various design parameters in order to optimize performance. As a tire wears, the parameter choices that optimized performance of the tire's tread pattern in the unworn state may not be optimal at reduced groove depths. For example, a new tire construction may be designed with a tread pattern having raised blocks in which noise reduction, due to the high nonskid, is a controlling factor. However, blocks that provide a balanced tire behavior in the new condition may not exhibit optimized noise reduction and hydroplaning control in a worn condition as the groove depth diminishes. As the tread wears, the noise created by contact between the road-contacting surfaces of the tread blocks and the road diminishes. However, worn tires with conventional blocks are significantly more susceptible to hydroplaning than new tires.
For these and other reasons, it would be desirable to provide a pneumatic tire that addresses these and other deficiencies of conventional pneumatic tires.